package com.nian.global.utils;

import java.util.Base64;

/**
 * Created by nian on 2023/4/16.
 */
public class Base64Utils {

    static private final int BASELENGTH = 128;
    static private final int LOOKUPLENGTH = 64;
    static private final int TWENTYFOURBITGROUP = 24;
    static private final int EIGHTBIT = 8;
    static private final int SIXTEENBIT = 16;
    static private final int FOURBYTE = 4;
    static private final int SIGN = -128;
    static private final char PAD = '=';
    static final private byte[] base64Alphabet = new byte[BASELENGTH];
    static final private char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];

    static {
        for (int i = 0; i < BASELENGTH; ++i) {
            base64Alphabet[i] = -1;
        }
        for (int i = 'Z'; i >= 'A'; i--) {
            base64Alphabet[i] = (byte) (i - 'A');
        }
        for (int i = 'z'; i >= 'a'; i--) {
            base64Alphabet[i] = (byte) (i - 'a' + 26);
        }

        for (int i = '9'; i >= '0'; i--) {
            base64Alphabet[i] = (byte) (i - '0' + 52);
        }

        base64Alphabet['+'] = 62;
        base64Alphabet['/'] = 63;

        for (int i = 0; i <= 25; i++) {
            lookUpBase64Alphabet[i] = (char) ('A' + i);
        }

        for (int i = 26, j = 0; i <= 51; i++, j++) {
            lookUpBase64Alphabet[i] = (char) ('a' + j);
        }

        for (int i = 52, j = 0; i <= 61; i++, j++) {
            lookUpBase64Alphabet[i] = (char) ('0' + j);
        }
        lookUpBase64Alphabet[62] = (char) '+';
        lookUpBase64Alphabet[63] = (char) '/';
    }

    private static boolean isWhiteSpace(char octect) {
        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
    }

    private static boolean isPad(char octect) {
        return (octect == PAD);
    }

    private static boolean isData(char octect) {
        return (octect < BASELENGTH && base64Alphabet[octect] != -1);
    }

//    /**
//     * Encodes hex octects into Base64
//     *
//     * @param binaryData Array containing binaryData
//     * @return Encoded Base64 array
//     */
//    public static String encode(byte[] binaryData) {
//        if (binaryData == null) {
//            return null;
//        }
//
//        int lengthDataBits = binaryData.length * EIGHTBIT;
//        if (lengthDataBits == 0) {
//            return "";
//        }
//
//        int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
//        int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
//        int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
//        char encodedData[] = null;
//
//        encodedData = new char[numberQuartet * 4];
//
//        byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
//
//        int encodedIndex = 0;
//        int dataIndex = 0;
//
//        for (int i = 0; i < numberTriplets; i++) {
//            b1 = binaryData[dataIndex++];
//            b2 = binaryData[dataIndex++];
//            b3 = binaryData[dataIndex++];
//
//            l = (byte) (b2 & 0x0f);
//            k = (byte) (b1 & 0x03);
//
//            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
//            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
//            byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
//
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
//        }
//
//        // form integral number of 6-bit groups
//        if (fewerThan24bits == EIGHTBIT) {
//            b1 = binaryData[dataIndex];
//            k = (byte) (b1 & 0x03);
//            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
//            encodedData[encodedIndex++] = PAD;
//            encodedData[encodedIndex++] = PAD;
//        } else if (fewerThan24bits == SIXTEENBIT) {
//            b1 = binaryData[dataIndex];
//            b2 = binaryData[dataIndex + 1];
//            l = (byte) (b2 & 0x0f);
//            k = (byte) (b1 & 0x03);
//
//            byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
//            byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
//
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
//            encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
//            encodedData[encodedIndex++] = PAD;
//        }
//        return new String(encodedData);
//    }
//
//    /**
//     * Decodes Base64 data into octects
//     *
//     * @param encoded string containing Base64 data
//     * @return Array containind decoded data.
//     */
//    public static byte[] decode(String encoded) {
//        if (encoded == null) {
//            return null;
//        }
//
//        char[] base64Data = encoded.toCharArray();
//        // remove white spaces
//        int len = removeWhiteSpace(base64Data);
//
//        if (len % FOURBYTE != 0) {
//            return null;// should be divisible by four
//        }
//
//        int numberQuadruple = (len / FOURBYTE);
//
//        if (numberQuadruple == 0) {
//            return new byte[0];
//        }
//
//        byte decodedData[] = null;
//        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
//        char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
//
//        int i = 0;
//        int encodedIndex = 0;
//        int dataIndex = 0;
//        decodedData = new byte[(numberQuadruple) * 3];
//
//        for (; i < numberQuadruple - 1; i++) {
//
//            if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
//                    || !isData((d3 = base64Data[dataIndex++])) || !isData((d4 = base64Data[dataIndex++]))) {
//                return null;
//            } // if found "no data" just return null
//
//            b1 = base64Alphabet[d1];
//            b2 = base64Alphabet[d2];
//            b3 = base64Alphabet[d3];
//            b4 = base64Alphabet[d4];
//
//            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
//            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
//            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
//        }
//
//        if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
//            return null;// if found "no data" just return null
//        }
//
//        b1 = base64Alphabet[d1];
//        b2 = base64Alphabet[d2];
//
//        d3 = base64Data[dataIndex++];
//        d4 = base64Data[dataIndex++];
//        if (!isData((d3)) || !isData((d4))) {// Check if they are PAD characters
//            if (isPad(d3) && isPad(d4)) {
//                if ((b2 & 0xf) != 0)// last 4 bits should be zero
//                {
//                    return null;
//                }
//                byte[] tmp = new byte[i * 3 + 1];
//                System.arraycopy(decodedData, 0, tmp, 0, i * 3);
//                tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
//                return tmp;
//            } else if (!isPad(d3) && isPad(d4)) {
//                b3 = base64Alphabet[d3];
//                if ((b3 & 0x3) != 0)// last 2 bits should be zero
//                {
//                    return null;
//                }
//                byte[] tmp = new byte[i * 3 + 2];
//                System.arraycopy(decodedData, 0, tmp, 0, i * 3);
//                tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
//                tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
//                return tmp;
//            } else {
//                return null;
//            }
//        } else { // No PAD e.g 3cQl
//            b3 = base64Alphabet[d3];
//            b4 = base64Alphabet[d4];
//            decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
//            decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
//            decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
//
//        }
//        return decodedData;
//    }

    /**
     * remove WhiteSpace from MIME containing encoded Base64 data.
     *
     * @param data the byte array of base64 data (with WS)
     * @return the new length
     */
    private static int removeWhiteSpace(char[] data) {
        if (data == null) {
            return 0;
        }

        // count characters that's not whitespace
        int newSize = 0;
        int len = data.length;
        for (int i = 0; i < len; i++) {
            if (!isWhiteSpace(data[i])) {
                data[newSize++] = data[i];
            }
        }
        return newSize;
    }

    // Base64编码
    public static String encode(byte[] data) {
        return Base64.getEncoder().encodeToString(data);
    }

    // Base64解码
    public static byte[] decode(String encodedData) {
        return Base64.getDecoder().decode(encodedData);
    }
}
